If each water molecule donates one electron, how much water is ionized in the lightning? One mole of water has a mass of 18.1 g/mol. Answer in units of g. Avogadro’s number is 6.02214e23 /mol. ok so this is what i did... (18.1grams/1mole)(1mol/6.02214e23 molecules)=3.005576e-23 this is wrong since it doesnt give the right units. How would i do this?